Running a backup script on Sql 2014 to a UNC path fails with error

Running a backup script on Sql 2014 to a UNC path fails with error (operating system error code 3(the system cannot find the path specified). We have tried to give full rights to the folder but nothing seems to be working. The backup job does works fine if we send it to the C:\ drive. Is there anything else we can try?
Thanks

Script i'm running:

--- Automatically do Full Backup of all databases simple Recovery Mode

DECLARE @name VARCHAR(50) -- database name  
DECLARE @path VARCHAR(256) -- path for backup files  
DECLARE @fileName VARCHAR(256) -- filename for backup  
DECLARE @fileDate VARCHAR(20) -- used for file name 

SET @path = '\\server-4\c$\BackupLocation\'  --Case Sensitive

SELECT @fileDate = CONVERT(VARCHAR(20),GETDAT<wbr ></wbr>E(),112) 
   + '_' 
   + REPLACE(CONVERT(VARCHAR(20<wbr ></wbr>),GETDATE(<wbr ></wbr>),108),':'<wbr ></wbr>,'')

DECLARE db_cursor CURSOR FOR  
SELECT name
FROM master.dbo.sysdatabases 
WHERE
    name NOT IN (N'tempdb') AND
    DATABASEPROPERTYEX(name, N'Status') IN ( N'EMERGENCY', N'ONLINE' )

OPEN db_cursor   
FETCH NEXT FROM db_cursor INTO @name 

WHILE @@FETCH_STATUS <> -1   
BEGIN   
       SET @fileName = @path + @name + '_Full_' + @fileDate + '.bak'  
       PRINT 'Backup Database command being issued on database "' + @name + '".' 
       BACKUP database @name TO DISK = @fileName WITH CONTINUE_AFTER_ERROR 
       --IF @@ERROR > 0
       --BEGIN 
           --add code here to record and/or notify yourself that an error occurred during BACKUP
       --END --IF
       FETCH NEXT FROM db_cursor INTO @name   
END  

CLOSE db_cursor   
DEALLOCATE db_cursor 

--REF
--Simple: No log backups. Automatically reclaims log space to keep space requirements small, essentially eliminating the need to manage the transaction log space. 
--Full: Requires log backups. No work is lost due to a lost or damaged data file. Can recover to an arbitrary point in time (for example, prior to application or user error). 

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